The present invention relates generally to a hydraulic lash adjuster assembly for use in a diesel engine having a compression release retarder. In particular, the present invention is directed to a system that permits an engine to operate under positive power with a hydraulic lash adjuster to remove unwanted lash and to disable the hydraulic lash adjuster when operating with a compression release retarder.
Today the use of hydraulic lash adjusters in heavy duty diesel engines is nonexistent or in limited use at best. However, with the technological advancements and discussions of hydraulic overheads, camless engines with hydromechanical valve control, and lost motion devices, the hydraulic lash adjuster is sure to be standard equipment before any of the other mechanisms mentioned. The hydraulic lash adjuster mechanism is a standard component in most automotive gasoline engines on the road today, and has become reliable for that industry.
A commonly used device added to the heavy duty diesel engine is a compression release retarder, also known as an engine brake. This device actuates one or more exhaust valves when the engine is in a braking mode of operation. The use of an automatic hydraulic lash adjuster on the exhaust rocker arms of an engine equipped with an engine brake may not work. The constant flow of oil to the hydraulic lash adjuster may cause the hydraulic lash adjuster plunger to protrude further out of its assembly during the brake operation, resulting in the valve not seating at the end of the engine cycle.
It is an object of the present invention to provide a hydraulic lash adjuster in a diesel engine having a compression release retarder.
It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine to remove unwanted lash during positive power.
It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine that can be disabled during a compression release retarding operation.
It is another object of the present invention to provide a hydraulic lash adjuster in an engine to permit modification of valve timing during positive power.
It is another object of the present invention to provide a hydraulic lash adjuster in an engine to permit modification of lift during positive power.
It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine for improved emissions during positive power.
Additional objects and advantages of the invention are set forth, in part, in the description which follows and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.
The present invention is directed a system for use in a diesel engine having a compression release retarder. The system includes a hydraulic lash adjuster assembly located on at least one of an intake rocker arm and an exhaust rocker arm. The rocker arms are pivotally mounted on a rocker shaft. The rocker shaft includes a passageway for each of the intake rocker arm and the exhaust rocker arm to provide a supply of hydraulic fluid to operate the hydraulic lash adjusters on the intake rocker arm and the exhaust rocker arm. At least one solenoid valve on the rocker shaft is provided to control the flow of hydraulic fluid through the passageways to operate the hydraulic lash adjusters on the exhaust and intake rocker arms. A control assembly is provided to control the operation of the solenoid valves. The control assembly controls the operation of the solenoid valves to permit operation of the adjusters during positive power and to deactivate the adjusters during a compression release retarding operation. Furthermore, the operation of the control assembly permits the lash adjusters to be operated to adjust valve timing during positive power.
The system also includes a brake rocker arm assembly having its own dedicated cam lobe or a conventional engine brake to facilitate engine braking.
The present invention is directed to an improved assembly for operating at least one exhaust valve and at least one intake valve in a cylinder in an engine. The assembly includes a rocker shaft, an intake rocker arm pivotally mounted on the rocker shaft for operating at least one intake valve of the engine cylinder, an exhaust rocker arm pivotally mounted on the rocker shaft for operating at least one exhaust valve of the engine cylinder. The improved assembly includes a lash adjusting assembly for adjusting a lash between at least one of the intake rocker arm and the at least one intake valve, and the exhaust rocker arm and the at least one exhaust valve. The improvement further includes a fluid supply assembly for supplying fluid to the lash adjusting assembly to operate the lash adjusting assembly. The improved assembly further includes a control assembly for controlling the operation of the fluid supply assembly in response to predetermined engine operating conditions.
A first lash adjusting assembly may be located on an intake rocker arm, wherein the lash adjusting assembly adjusts the lash between the intake rocker arm and the at least one intake valve. A second lash adjusting assembly may be located on an exhaust rocker arm, wherein the lash adjusting assembly adjusts the lash between the exhaust rocker arm and the at least one exhaust valve. Finally, the improved assembly may include a pair of the lash adjusting assemblies to adjust the lash between the exhaust rocker arm and the at least one exhaust valve and between the intake rocker arm and the at least one intake valve.
The fluid supply assembly may supply hydraulic fluid to the lash adjusting assembly to operate the lash adjusting assembly. The fluid supply assembly may comprise fluid passages in the rocker arm to supply hydraulic fluid to the lash adjusting assembly. The fluid supply assembly may further include passages and a solenoid valve located on the rocker shaft.
The control assembly may operate the fluid supply assembly to supply fluid to the lash adjusting assembly during positive power. The control assembly may operate the supply assembly to deactivate the lash adjusting assembly during an engine braking operation. The control assembly may operate the supply assembly to deactivate the lash adjusting assembly after the control assembly senses a predetermined engine operating condition. The control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify valve timing of at least one of the at least one exhaust valve and the at least one intake valve. Furthermore, the control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify valve lift of at least one of the at least one exhaust valve and the at least one intake valve. Additionally, the control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify overlap of the at least one exhaust valve and the at least one intake valve.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference, and which constitute a part of this specification, illustrate certain embodiments of the invention and, together with the detailed description, serve to explain the principles of the present invention.